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Does the AP disengage if the plane is upset and how would the flight controls react if not being held?
Does the AP (autopilot) essentially detect a rapid change in speed/altitude as a wild maneuver? If so, upon disengaging, if the pilots are not holding the control column in a neutral position, will it move in whatever direction the plane is going?
For example, a steep climb that wasn’t anticipated, and no one holding the Column, will it fall back towards the pilots, ultimately making the steep climb worse?

Are you asking about a particular aircraft, reversible or FBW aircraft? The answers will differ.

For non FVW airplanes:
Yes it will disengage if certain pitch and roll attitudes are exceeded.  When it disengages, the controls are "let go" if the A/P was applying an input at the time, and the control column will move to whatever its natural trimmed state is at that time if the elevator is manually operated with trim tabs.
If the airplane has irreversible hydraulic controls and an artificial feel system and a trimmable stabilizer, the column will just spring back to neutral and the airplane will seek its existing trimmed speed.  If the trim speed is the same as the current speed, pretty much nothing happens, if the trim speed is much different that trim speed, the nose will pitch up or down to try to accelerate or decelerate to the trim speed set by the current state of the pitch trim system.
It's as if your copilot was flying, minding his own business, and you shot him dead.  The column will just go to wherever it wants to go when no-one is holding it.  The airplane has natural static "stick-free" stability so it will seek its natural trimmed state and if the A/P input was different from that, it'll just start going where it trim state wants it.  As if you pulled on the column and then let go.
On an airplane with control cables, the autopilot is a little computer running a bidirectional electric winch (the A/P servo) back in the tail who's winch cables are tied into the elevator cable run.  It drives the cable circuit from back there instead of from the column.  The autopilot also usually works the pitch trim that same way a human pilot would, to relieve the need for the servo to hold control pressures beyond a small threshold same way a human would.
So if the airplane was more or less in trim when the A/P kicks off, not much happens.  If the airplane was in some crazy attitude because of some outside event, the A/P kicking off is like you were flying and got flipped over and you took your hands off the controls to cover your face in fright (that's what I would do lol). The controls will just return to where they are trimmed to go to in that state.  On most airliners with powered controls and a moveable stab, the column always springs back to the same neutral position regardless of trim state.
If the a/c is FBW, the A/P is integrated into the computers that actually run things and it gets a lot more complex, although the end results are not that much different.

Poor Co-Pilot :(

From what I have learned in university and my personal experience as a glider pilot, airplanes are not roll stable. They will fall into a turn at some point and not continue straight forever. The time period for that is really long, could be minutes before the bank angle exceeds 5 degrees if the aircraft is trimmed correctly and flying straight and level. A tiny aileron correction is all that is needed and therefore it is accepted as being unstable but easily controllable.But if you're already at 30 degrees of bank things get worse quickly

Well sort of are, within a range. Gliders on the other hand are designed to be more or less roll neutral, so it tends to hold whatever bank angle you set, for easy thermalling.  I've been flying a SZD-51 Junior this summer and it is wonderfully roll neutral.  But yes most airplanes are roll stable within a narrow range and if upset beyond that they will naturally start to spiral, a function of sideslip + weathervaning tendency.  So in reasonably smooth air an airplane like a 172 will carry on by itself for quite a while until something upsets it enough to overpower its roll stability.

It's hard to provide a specific answer because a lot of important context is missing from your question, but here goes.
In a conventional airplane, with any manner of control system, when the stick is released from a held position where there is deflection of the control surfaces, the stick should return to centre.
In salt-of-the-earth cable driven control systems, the act of pushing the stick in any direction causes control surfaces to move up into the airstream. The drag that this produces creates resistance, a weight that is felt in the stick. When you let go, the stick will spring back due to this resistance, and probably over centre into the opposite side and cause an oscillation, but that will dampen out and the stick will rest neutrally.
This self-aligning force can be felt when you're driving a car at relatively high speed. Imagine you're on the highway and to follow the road, you need to make a gentle
Even in systems where there are not direct connections between the stick and the surfaces, engineers add artificial means to produce this feedback. For example, in some fighter jets the stick has an extension under the floor which has a deadweight attached to it, which the pilot has to pull against to hold the airplane at a certain level of G-loading when turning.
This self-aligning force is very important to how the aircraft feels in the hand. It can also be felt when you're driving a car at relatively high speed. Imagine you're on the highway and to follow the road, you need to make a gentle curve. Then imagine you turn the wheel and it's as light as a feather.. it would be very difficult to find and hold the precise input required to produce the required turn.
In your scenario, when the airplane is climbing and the stick is released, it may fall backwards a little bit initially, but it will not accelerate like a dropped object straight to maximum deflection because the airplane itself is resisting the force gravity as it's applying itself to the stick. it will find a neutral point just aft of centre stick
None of this means to say that the airplane will climb or descend, or even maintain the same angle of bank. You haven't defined enough variables in this scenario (Airspeed, pitch angle, power setting, trim setting, engine type) to tell us what might happen next.
I will leave the autopilot part of the question to somebody who's even remotely qualified to talk about that.


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How did the Brazilian Civil Aviation Authority have MCAS on paper from Jan 2018?
 how could they know but nobody else did? Did they buy the extra sensor or something?

I'm not really understanding the question here. MCAS wasn't a secret, so I'm not sure it's surprising a regulator was aware of its existence. There are certainly arguments that regulators didn't scrutinize it enough, that pilots weren't given enough training on it, etc... but it's not as if the Brazilian authorities were the only people to know of its existence.

@ZachLipton from what I know, reading the many articles that have been published by the media, pilots nor airlines knew about MCAS.

Some pilots didn't know about it, or didn't know enough about it, and there's considerable question about Boeing hiding the reality of the system from regulators, but that's different than the basic existence of the system being a secret. Boeing at the time was "jedi-mind tricking regulators into accepting the training that I got accepted by F.A.A," essentially convincing regulators that while the system existed and was certified, it didn't need to be included in the pilots manual or differences training.

And the document you've posted is exactly part of that process. MCAS is listed as a difference between the 737 models on the Operator Difference Requirements, and regulators have a whole process where the manufacturer demonstrates the significance of each difference and the level of training required for pilots on the change.

Of course the airlines knew about MCAS.  Do you think the maintenance manuals, maintenance program documents, tech training, wiring diagrams, and all that stuff was left out so it was totally top secret?  There would be a controller, wiring and software on board even though there were no cockpit indications or controls, so certainly the techs who might have to troubleshoot it, and others on the tech/engineering side, would know.
All that happened was MCAS was excluded from differences training, as that document shows, so that it was not included in the ground school differences course pilots took when moving from one 737 model to another (avoiding sim time, which was the point).
So pilots never got a formal briefing on its existence, and it could just be considered part of the "PFM" of the various black box systems who's level of function is too in-depth to be included in pilot training (PFM means "Pure F-ing Magic" and is a term instructors use to describe black box function that is beyond the training because covering it would extend the course to months).
I have little doubt there were pilots, those who dig into the aircraft more deeply than most and might even peruse maintenance manual descriptions, who would have known of the system, but just not on an official level, with official procedures and protocols that affected the flight crew.
Sort of like the subsystem that applies the brakes after you lift off to spin the wheels down right away. It just does its thing in the background, and pilots may or may not be aware of it, but everybody on the technical side does.

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Is the point of “groundspeed” in aircraft just to have a second reference of speed but two totally different measurements of speed?
From not understanding groundspeed will always be significantly higher than airspeed, unless the plane is pitching up and down. Is the ground speed just there for pilots to look at and say “okay we have x amount of airspeed and x amount of ground speed, so we’re okay”?
To explain a bit better, I’ll give a scenario I’m thinking of when something would be confusing or just off to the pilots:Airspeed is decreasing rapidly but groundspeed is staying the same, the planes pitch is also the same.
Would this be an indicator of unreliable airspeed or something different? Or is there an actual phase of every flight where the pilots needs groundspeed?

Your understanding is wrong.  Ground speed can be much higher than air speed, or much lower.  It depends entirely on the wind.  With a small plane in a stiff headwind, you could even have negative groundspeed.  You need groundspeed for figuring out when you'll be getting to your destination, and if you have enough fuel. With a stiff headwind, it will take much longer than if you calculate the time from your air speed, while with a tailwind, you might overshoot your destination and have to turn and fly back.

Airspeed dictates how (and if) a plane flies because it relative to the air that the plane is flying through, the only thing that matters for aerodynamics.
Groundspeed can be greater or less than the airspeed depending on which way the air is moving over the ground, i.e. wind.
The latter is only important for figuring out when you'll arrive at your destination (and related things like ensuring you have enough fuel to keep the engines running that long); for everything else, the former is what matters.

I would argue that groundspeed is more important than just knowing when you arrive at your destination. If you don’t monitor your ground speed, and the resulting fuel consumption, you won’t be arriving at your destination at all.

Indeed, I'd argue that (except for takeoff and landing) airspeed is not all that relevant for normal flying.  You take off, climb to your cruise altitude, set your throttle to desired RPM/power, and it stays there until you're ready to descend for landing.  Ground speed determines whether you make it to your destination before you run out of fuel, overshoot your destination and have to turn back, or (with crosswinds) wind up well to one side or the other of your destination.

The groundspeed can be more, less or the same as the airspeed.
Go back to boats.  I'm driving around in my boat on a big river with a 5 mph current.  My boat goes 30 mph.  If I'm going with the current, my boat is going 35mph relative to the river bottom and the shoreline.  If I turn around and go the other way, my boat is going 25mph relative to the river bottom and the shoreline. If I go across the current, it's a wash and my boat speed and speed over the river bottom is the same, as if there was no current.
My boat's water speed is 30 all this time.  My boat's "river bottom speed" is water speed plus or minus the effects of the current.  As far as the boat itself goes, it doesn't know or care what direction its going relative to the river bottom, it's just concerned with the speed relative to the water surface, which is moving relative to the bottom.
An airplane is flying along a "river" of air and it has its airspeed, the speed through the air mass, and it's speed relative to the surface the air mass is flowing over, the "river bottom", or the ground in our case.
The pilot's main concern with groundspeed is the same as the boat captain's concern with boat speed added or subtracted from the current (say when navigating in the ocean). It affects how long it will take to get from A to B, and how much fuel will be required, and related things.
It doesn't have much effect on the flying of the plane itself except in an extreme case like a windshear encounter, where the inertia of the airplane itself can be a factor.  The case you describe could be what is called a "reduced performance shear", which is a very sudden and extreme tailwind, which makes airspeed drop while groundspeed stays the same or increases fairly slowly.  An airliner on approach that ends up with a downburst behind it, and is caught in the high velocity outflow of the downburst from behind, would see that happen due to the inertia of the aircraft until it's able to recover it's original speed through the air mass.  While it's doing this it would have to pitch up and use some of its inertial energy to keep from descending below the glide path.
Even there though, you aren't really concerned with the groundspeed itself, except to the extent that the groundspeed affects how quickly go from A to B on the approach.  You are totally concerned with recovering the lost airspeed that the airplane needs to fly.

I pocket-dailed the downvote button, sorry. If you make an edit I can revert it to an upvote.

Groundspeed is the MOST important speed to know when it comes to flight planning, and flight monitoring. If you don’t know how much time it will take to arrive at your destination, you may never arrive.
There is is only a finite amount of fuel in your tanks. Every flight has to use estimated groundspeed before the flight, and actual groundspeed during the flight, to know if you have enough fuel to reach your destination.
If you fail to monitor your groundspeed, you may run out of fuel short of your destination. In that case indicated airspeed would become important as you try to glide your aircraft to a safe landing.

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Why does the Pratt & Whitney 747 have an extra engine on the right side but not left side?

What’s the purpose of this design, and why only on one side?

You should add a reference to the original picture. I'm quite sure this is a testbed and its goal is to test the extra engine in flight (i.e. this engine is not here to provide thrust)

A good question would have been "why do they add a pylon instead of replacing one existing engine with the tested one?"

@ManuH True, but that question can only be asked once you know this 747 is a test bed. The additional engine might as well provide extra thrust or just get carried around, like Quantas did.

It's an engine testbed aircraft. In this particular picture, the tested engine is probably one of the PW1X00G series (mainly used by Airbus A220, Airbus A320neo, Embraer E-Jets E2, Irkut MC-21, Mitsubishi SpaceJet) and the aircraft is one of two Boeing 747SP testbed aircraft owned by PW.
Engine testbed aircraft test the engines in-flight, with parameters and conditions that can not be tested in a static test on the ground (for example, low temperatures and non-static thrust).
Engine testbed aircraft often end up in unusual configurations. Other examples include (but not limited to):

General Electrics Boeing 747 testbeds: 1 2
Honeywell's Boeing 757 testbed: many pictures with different engines, even turboprops.


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How did the Boeing 777X's main landing gear lift before the nose on its first takeoff?

Source: Boeing 777X Takeoff for its First Flight
Is this from a low payload and the configuration of flaps? Or perhaps a pilot pushing the yoke forward while the plane wants to lift?

This is an optical illusion, as the nose gear aligns with the edge of the runway.  It is actually at least 3-5 feet off the runway when the right gear lifts off.  The nose gear lies midway between the left and right mains in the roll plane.  In order for it to be in contact with the runway when the right main lifted, the plane would have to pitch down.  That is not what happened here.

I gotta say, at this time stamp the right MLG is definitely off the ground, but there still appears to be a plume of spray behind the nose wheel. If you watch full screen on a large monitor, it very much seems to be there. It's not until here that I can see the nose wheel lift.

Correct on both guesses to some extent I would say.  The airplane is pretty light, and with flaps down the flapped area of the wing is operating at a positive AOA (remember that the chord line is from the LE of the slat to the TE of the flap, so with flap down there is positive AOA even while 3 point).
Also as it's an initial test flight I wouldn't be surprised if the pilot delayed rotation past normal Vr 5 or 10 kts just to have some extra energy margin if something went amiss, so not necessarily holding the nose down, but delaying pulling it up.
Added together, maybe helped by a bit of crosswind coming from that side, you get the truck starting to come off before rotation.

and maybe he tried to keep it down for the cameras as well, give the press and marketing guys a few extra seconds to get their photos of the first takeoff.


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Why does the KC-46 use two sensors for MCAS when the 737 Max doesn’t?
this article states

The KC-46 has a two-sensor MCAS system, which “compares the two readings,” the Air Force said.

I’m aware that the 737 uses two sensors and always has, but the computer reads them simultaneously based off which pilot is flying the plane. So if the Captain is flying it’s reading data from the left side, correct?
At this point I’m assuming Boeing’s decision to pull data from one sensor was to reduce the workload and make for a earlier introduction?

Regarding Boeings decision to use single sensor data for MCAS, words that come to mind are stupid and reckless. The Air Force was most likely smart enough to demand a system with some basic redundancy.

Also a guess: There was no pressure to carry over a type rating for pilots of a previous model.

@Jpe61 redundancy is very important for the military. Furthermore, I believe that the military is in a much better position to gain insight into a plane's design; and if they see a need, to demand changes. MCAS was deliberately designed by Boing so that the MAX falls under the 737's existing certification. If the 737 MAX fulfills all existing regulation, on what grounds could the FAA demand changes to the MCAS?

@MSalters So if Boeing changed the computer, and opened it up to read two sensors at once, the plane now requires additional training?

@Firefighter1: You then need to compare them. And since you only have two, in case of conflict you need a pilot procedure in case the readings differ too much. Can't vote with just two sensors.

No, MCAS does not read Data from the flying pilot side. MCAS gets AOA data from either FCC 1 or FCC 2 and this is automatically alternated for each flight. FCC 1 uses the left AOA and FCC 2 uses the right AOA.

@Firefighter1 "So if Boeing changed the computer, and opened it up to read two sensors at once, the plane now requires additional training? ". Yes indeed. Upon a discrepancy in outputs the system will warn the pilots and switch off, since there iss no way to tell which one is wrong in case of 2 systems. The flight crew will then need to be trained in handling the aeroplane in the circumstance that the system was designed to deal with.

The number of sensors used to provide a parameter is driven by the criticality of the function that uses the parameter as well as the operational philosophy behind the architecture of involved systems, which for the 737 is "same-side only" for sensors, computers, displays and controls, to facilitate fault isolation and resolution. Thus the left display & FCC get airspeed, altitude, AOA from ONE resp. sensor on the left, the left SMYD computer gets AOA from L sensor & drives L control column stick shaker. Ditto for right. Exception: only one FCC can be active & operate both flight controls.

With one sensor feeding a side, when discrepant, backup is the other side, pilot arbitrates which one is valid by comparing with standby ASI, altimeter. AoA value is not critical to pilots or autopilot—unlike Airbus, the autopilot doesn't override pilots inputs, so automated source select to maintain availability & reliability of params not necessary. MCAS operation is not safety-critcal. On 767 KC-46 MCAS used with refueling operations, critical enough to require 2nd sensor (for validity monitoring) but not 3rd (reliable redundancy).

According to the article, the KC-46 uses the dual FCC/AoA sensor for computing both FCC channels and comparing the command signals. With two disagreeing signals there is no way to determine which one is correct and the usual remedy is to disengage both, warn the pilot, and engage in the appropriate crew procedure. And that requires training.
The B737MAX was promoted as requiring only very limited differences training relative to the NG, so the setup for the KC-46 could not be copied. The original design of MCAS in the B737MAX also used two transducers for activation - two different types of transducers, both of which had to be over a threshold value, as mentioned in this answer. Original design MCAS only had limited authority of 0.8 deg stabiliser. From the crash report of Lion Air 610, page 204:

MCAS is designed to function only during manual flight (autopilot not
engaged), with the aircraft’s flaps up, at an elevated AOA. As the development of the 737-8 (MAX) progressed, the MCAS function was expanded to low Mach numbers and increased to maximum MCAS command limit of 2.5 of stabilizer movement.

The report states that in the failure analysis, Boeing classified the uncommanded MCAS failure condition as Major (which may not occur more than once in 10$^5$ flying hours), instead of Hazardous (1:10$^7$) or Catastrophic (1:10$^9$) allowing for indeed a single transducer input. Again from the report, page 206:

If the probability of an undesirable failure condition is not below the maximum allowable probability for that category of hazard, redesign of the system should be considered. If the uncommanded MCAS failure condition had been assessed as more severe than Major, the decision to rely on single AOA sensor should have been avoided.

Why all of this was done for the B737, while the KC-46 uses two sensors, is a conglomeration of factors. Two sensors is best. Time pressure for plane delivery, airline customer pressure for limiting differences training, the observation that previous versions of B737s with accumulated flying hours of 250 million had experienced no catastrophic failures due to AoA sensor failure (reference again from the crash report), all led to the perhaps justifiable belief that the one sensor was sufficient. If rapid action was taken by the crew to contain the failure - but the failure could not be reognised in time. Again page 206:

During the single and multiple failure analysis from the air data system worst case scenario of “failure of one AOA followed by erroneous AOA”, Boeing concluded that the effect would be hazardous until the flight crew recognized the problem and took appropriate action to mitigate it. Since the training or the guidance for actions taken in such situation were not provided, the effect category should have remained hazardous.
Since the FCC controlling the MCAS is dependent on a single AOA source, the MCAS contribution to cumulative AOA effects should have been assessed.

This may be grounds for a new question. If I'm reading correctly, a failure happening 1 in 10^5 hours is Major, while a failure happening 1 in 10^9 is Catastrophic? How's that? 10^5 is a much smaller number (and therefore much more frequent occurrance) than 10^9. (Or is that a typo?)

@FreeMan A Catastrophic failure may occur not more than 1 in 10$^9$ flying hours, a Major fail does not have catastrophic consequences per se and is allowed to happen no more than once in 10$^5$ flying hours.

Ah, that makes more sense. Thank you!

@FreeMan Thanks for the comment, have improved the phrasing in the answer.

Two sensors is better, three (or more) would be best.

@Berend No, failure rate of all the components in the system need to be considered, plus the actions taken when a component fails. System design for functionality, as successfully implemented in the KC-46 MCAS, where AoA sensor fail could be detected, then MCAS switched off and the pilots notified. This was the bit that the MAX did not implement.

We can't know why Boeing did what they did unless they tell us and given the legal implications of saying too much there's more noise than signal.  I can speculate with the rest on an answer with the rest of them.
The 737MAX MCAS was meant to provide a certain "feel" on the control yoke to the pilot when making specific maneuvers.  MCAS would be expected to make minor corrections to the trim, do so rarely, and any failure was expected to look like a runaway trim or other failure that pilots were already trained to address in the 737NG.  This was not considered a flight critical function and so used only one sensor.
On the KC-46 the purpose of MCAS was to mitigate the shifting center of gravity as fuel was being delivered to other aircraft.  MCAS would be in near constant operation, it had what was believed to be far greater control of how the aircraft performed, and so used two AoA sensors for redundancy of input.
As I recall the decision to use only one AoA sensor was not to reduce workload on the engineering and testing but to reduce workload on the computers in the aircraft, computers that already had considerable workload for their capability.  One AoA sensor meant not needing to take the extra computing power to check one input against the other.
I wish I could recall where I read this but someone that claimed to know what he was talking about said that it would have been possible to not only compare one AoA sensor against the other but to compute the AoA from other sensors to determine which sensor was giving good data if there was a disagreement.  This is in effect a "virtual" AoA sensor so that there can be a vote of 2 out of 3 on what is the correct AoA.  Additionally this was supposedly possible without exceeding the computing power of the 737MAX onboard computers.  Assuming this was possible that would have meant additional work to create this software and validate it was safe.  Given Boeing had a tight schedule, and MCAS was not considered safety critical by the FAA, this extra work was not done.
While the AoA sensors are on all 737MAX aircraft not all have this information available to the crew.  The crew would only be told of an AoA sensor mismatch if the airline purchased the option for AoA indicators on the flight deck.  This was apparently not a popular option, few 737MAX aircraft had AoA indicators.  Again, there are two AoA sensors on all the 737MAX aircraft but not all aircraft had AoA indicators for the crew, MCAS had this information but the crew might not.
Airbus apparently views AoA indication differently.  They put three AoA sensors on their aircraft so that single sensor failures can be detected and corrected.  Again, there is a claim that Boeing could correct for a single AoA sensor failure by computing AoA from other sensor inputs but they chose not to.  It's possible they chose not to out of legal reasons as much as practical and technical reasons.  If they demonstrated the ability to calculate AoA in order to detect and correct for a single AoA sensor input failure then that could open up another investigation on why this was not done before.
Boeing may have to dig in their heels on maintaining that AoA is "nice to know" rather than vital to controlling the aircraft so as to not attract more lawyers.  I don't know how important knowing AoA is to a pilot as I am not a pilot.  I expect this to be debated for some time.

Your downplaying of the 737MAX MCAS paints a wrong picture. While the MCAS of the KC-46 corrected stabilizer trim only once and only by 0.6 degrees, the 737MAX MCAS would do so repeatedly and by a much larger amount of 2.5 degrees of trim until AoA would drop below its limit (I believe that was 8 degrees). With a sensor malfunction this required reaction within 4 seconds to follow the procedure for trim runaway.

" Your downplaying of the 737MAX MCAS paints a wrong picture. "  I'm not downplaying the severity of the 737MAX MCAS problems, I'm answering the question on why Boeing would decide to have a single AoA sensor for MCAS and the FAA would agree to this decision.  This was done because at the time MCAS was not seen as safety critical or posing a safety problem of its own.  We know now this was not true but that's 20/20 hindsight.

"why ...  the FAA would agree to this decision" This was entirely because the FAA learned only after the crashes of the modifications to MCAS. All previous certification work was done by Boeing employees. If you had followed the link you would have learned that "Boeing Authorized Representatives are Boeing employees who are granted special permission to represent the interests of the FAA and to act on the FAA’s behalf in validating aircraft systems and designs’ compliance with FAA requirements".

@PeterKämpf  I know that the FAA was not aware of the implications of the changes made to MCAS on the 737MAX.  Again, the question was, why would the FAA agree to this?  The answer, they were not aware of the implications.  I am quite aware of the flaws in the system to verify that MCAS was not a safety hazard.  Because they did not know of this the FAA agreed that there was no need for a redundant AoA sensor input to MCAS.  I addressed your complaint already, why repeat it?  What do you want from me?


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Would it be frowned upon that with a uncommanded nose up, the pilots just do a full loop?
So what I’m asking is that if a uncommanded nose pitch up happened and was so bad that it reached a pitch angle of 50 degrees, the pilots were unable to stop the pitch up by applying the control column forward, would it be justified if the pilots just applied more back pressure, ultimately doing a full loop?

No airliners aren't stressed for loop maneuvers.  The proper action for that kind of extreme pitch attitude is to roll 90 degrees and let the nose fall, then roll level as the horizon is passing.  Of course if you had a nose up stab trim runaway that left you stuck with that pitch tendency (effectively a much lower trim speed), you're back to square one.
You have to slow down to as close as you can get to the trim speed that the nose-up-stuck stab wants to fly at.  You might find that you have enough elevator authority to maintain a level pitch attitude if you get the speed down to a minimum flaps up speed, say 180kt.
Then you can do other things to create a nose down pitching moment, like dropping the gear, and on most airplanes, extending flaps.  That should be enough to remove most or even all of the elevator input required depending on where the stab was when you killed its runaway.  In an extreme case where you've run out of options, you might even try getting passengers to move forward.
In recurrent sim training, a nose up stab runaway was always a more pleasant exercise than a nose down one.  Mostly because slowing down, and gear and flaps helped, and to the extent you had to hold continuous nose down elevator, one of you could brace your knee against the column to help with most of the push force and it was easier to hold it for extended periods.  A nose down stab runway was a much more difficult situation.

As an aside, hang glider pilots, who deal with relatively limited pitch control authority as a fact of life, are well versed in the utility of increasing the bank angle to help bring the nose down, when some sort of turbulence-induced situation or some sort of aerobatic maneuver has caused the aircraft's pitch attitude to rise higher than desired.

Well, in the world of radio-controlled model airplanes, there are some aircraft (e.g. long-winged gliders) that are prone to entering an uncommanded nose-down "tuck", which is best escaped by giving a firm nose-down input to fly through half of a downward loop to enter inverted flight.
But if I were a passenger in a plane that was doing an unexpected loop, I would probably be frowning.
Anyway, as far as normal (upward) loops go-- you really don't want to mess around with off-the-cuff spur-of-the-moment loops unless you know with absolute certainty that you are entering them with sufficient airspeed and pulling sufficient G's to get well past the upside-down attitude with sufficient flying speed. Otherwise you are in danger of entering of a tailslide after running out of airspeed with the nose pointing steeply upward.  Very bad for the control surfaces.
Of course, retaining too much airspeed as you transition through level inverted flight into the start of an inverted dive, can also be a very bad thing.
So be careful when looping.
Basically, a loop is never going to be a practical approach to dealing with something that is unexpectedly going wrong with a conventional full-scale airplane, unless something is seriously broken in the control system, and maybe not even then.  In almost all cases of an unexpected pitch-up, it would be better to increase the bank angle to help bring the nose down, if elevator inputs alone are somehow not doing the job.

No it would not be a good idea, nor justified and it would be frowned uppon, aside from the fact this is not a great idea for an untrained pilot this would simply stall the plane. Most aircraft lack the thrust to do a full loop in this manner. Pulling up aggressively even at full power generally leads to a "power on stall"

@quietflyer - haha corrected to explain a bit more clearly.

Yet gliders with zero thrust can do it-- its all a matter of having the appropriate entry speed and a good aggressive pull on the stick... if it's a half-hearted effort it will probably not end will...

@quietflyer: Gliders can do it because their stall speeds are enough lower and their L/D ratios enough higher than most airplanes that they don't need to exceed Vne in order to pull up into a loop and still be maintaining flying speed at the top of the loop.


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Is it true pilots in a smaller aircraft have the option of using the right or left door as rudder, to offset the actual rudder if failed?
So if the rudder fails or gets stuck in the “left” position a pilot could open the right door and it would essentially counter the effect?

A little, yes, but it's extremely ineffective because it's so far forward. Most small aircraft will fly fine with an inop rudder as long as the rudder isn't stuck in some extreme position.

How would you open a door and hold it open against a 120 mph wind?

@CareyGregory If your rudder fails (cables snap or gets stuck) in flight, you'd want to get about as slow as you are comfortable going. The rudder is a lot less effective as speeds slow down, so the slower you go, the easier it is to control by other means. But yes, even at 65 knots, the door is very hard to open (and close), I have quite a bit of personal experience with that unfortunately.

@CareyGregory kind of. But more so how would it react to counter the rudder stuck in a certain position

"How would you open a door and hold it open against a 120 mph wind? "  -- if it's hard to hold open, that's a good thing.  Indicates lots of sideforce is being generated.  Not unrelated to yaw torque.

If you happen to be flying say a Piper Cherokee, you don't have the option of opening the left door, 'cause there isn't one?  But it's also hard to imagine a situation (other than perhaps a crosswind landing) where you'd ever have more than a few degrees of rudder, or where a rudder failure would do anything but leaving it free in the airstream.

@RonBeyer please re open the question as it has not been asked before.

I'm only one of 5 votes to close. If you want it reopened, please edit to explain the difference between this and the linked question.

@RonBeyer Re flying at low speed when the rudder fails, my understanding was that you want to fly faster than the crossover airspeed if there's a rudder hardover. Above the crossover airspeed, the ailerons can overpower the rudder; below the crossover airspeed, the opposite happens.

@Firefighter1 Have you read the answers to the linked question ("How does turning a small plane by opening the doors work")? If so, can you explain what else you'd like to know that isn't answered by the answers over there?

@TerranSwett This may be true for commercial aircraft, but how many GA aircraft do you know with a published crossover airspeed, if they even have one? I know that my ailerons in my 177 have a lot more authority than the rudder does, even at slow speeds (given I can side-slip to a landing and still maintain directional control).

In reality, in a strongly- deflected stuck-rudder situation, the pilot would be best advised to forget about the doors and just land the plane, selecting a runway with a strong crosswind component if at all possible.  After all, when landing with a strong crosswind, it's not that uncommon to hold the rudder at close to full deflection in the "downwind" direction.  If no crosswind runway is available, the pilot will just have to land the plane going a bit sideways-- no problem if the aircraft happens to have tricycle gear, like most do these days.
Obviously, in a stuck-rudder situation, steering corrections must be accomplished entirely via bank angle changes via the ailerons.  Keeping the rate of change of aileron deflection (and bank angle) low will help smooth things out.


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How would a pilot stabilize the aircraft after a dual engine failure?
Since there would be no more thrust, they would have to exchange energy by losing altitude to keep forward speed. But what happens towards the end, when you have to reduce your V/S to something like -800/min, would a pilot for a commercial airline, flying a commercial jet, stabilize his aircraft with flaps? Or would they just drop in altitude quickly to have a high airspeed and then just let it run off by leveling out and dropping the landing gear?

what do you mean by "stabilize"? don't airplanes usually stabilize themselves?

How many engines does your airplane have?

Rather than put up with one us speculating and pontificating on what to do, just read this terrific account of the Air Canada Gimli Glider incident, where a '67 did exactly that. They pretty much did it right, helped by a Capt that really knew how to fly as opposed to just being competent at running the machinery.

There are a number of other examples of airplanes losing all engines, yet landing safely (or managing a restart).  Wikipedia actually has a list of commercial flights: https://en.wikipedia.org/wiki/List_of_airline_flights_that_required_gliding


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How do aircraft manufacturers determine the elevator size?
I’ve heard some pilots say the MD-11 (I think?)was made with too much elevator, and that it’s an overkill.
So now I’m curious, how do they determine the length for the elevator? Is it possible to make one that can be called an “overkill” without it having drastic effects on the flight?

Aeronautical engineering is where it's at. The elevator, or horizontal stabilizer, depending on the plane, has to be large enough to move the tail down to rotate for takeoff, and to move the tail down to flare for landing.  Once airborne and moving faster, not as much tail movement is needed to move the airplane up and down.  In my plane for example, once at cruise speeds the stabilizer really stiffens up, while at takeoff/landing speeds it is quite maneuverable with just one hand, the other being busy on the throttle, adjusting the prop, flaps, etc.

There are many factors going into the sizing of elevators, and they are all interconnected with other considerations such as CG envelope, static margin, flight controls, etc.
Here are some factors that will influence up-sizing the elevators. Usually, the minimum elevator sizing is determined by low speed requirements:

Ability to perform early rotation in both all engine operating and one-engine-inoperative conditions (14 CFR 25.107(e)).
Ability to perform go-around in the highest flap extended position (14 CFR 25.119).
Ability to stall the aircraft to demonstrate the intended stall speed (14 CFR 25.201). This may not be obvious, but if you lack the elevator authority to demonstrate the intended stall speed, then you can only declare what you have demonstrated, which negatively impacts all the performance speeds for takeoff and landing.
If the elevator is power actuated (e.g. hydraulically powered), then you also need to consider regular takeoff, landing, go-around, and maneuvering at low speed, with failures (14 CFR 25.671(c)).

Here are some factors that will influence down-sizing the elevators:

Demonstration of static longitudinal stability at Vmo/Mmo. For column based inceptors, the average stick force to speed change must be no shallower than 1 lb per 6kt (14 CFR 25.173(c)). For FBW aircraft, too large an elevator can also lead to residual oscillations.
General over-sensitivity to control inputs at high airspeed.

Of course, most of these aforementioned points are heavily influenced by flight control design, such as anti-servo tab, bob weights, artificial feel force, etc.

Your answer was so complete I decided to delete my own answer!


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How much thrust is applied in a 737 to achieve taxi speeds?
I'd imagine not much, but maybe none? I wouldn't be surprised if the plane moves forward without brakes alone.

It's definitely not none. You'll hear the engines spin up significantly past idle when a commercial airliner taxis. The answer is going to be "it depends" - if Kennedy Steve is asking you to get a move on, you'll probably use more to get up to speed faster, or if you're going up a slight grade.

The CRJ200 had too much idle thrust and would slowly accelerate on level ground to probably 20kt at idle.  You're not supposed to ride brakes so you have to apply them on and off to keep from going too fast,although if you do single engine taxi that takes care of it for you.  The bigger RJs needed more than idle to get going, and most larger airliners also do.

Aircraft weight, slope of the tarmac, and headwind or tailwind play a huge role in this. With a heavy aircraft, it can take significant power to start moving. However, a light aircraft, particularly with a little tailwind or favorable slope, may be ready to roll with idle thrust as soon as the brakes are released. The Max aircraft, particularly, generate more thrust at idle than the NG's so, and on those especially, advancing power is often unnecessary to start rolling.
Typically, though, advancing to 30 to 35% N1 is generally what a Next Gen takes to get rolling.
Interestingly, asphalt, which some of the taxiways at LGA and DCA are made of, can be harder to get moving on, especially in warm weather. The tires sink in just slightly, and it can take significantly more power than usual to get going - maybe even more than the 45% "maximum" value in sufficiently adverse conditions. Ideally, you'd like to keep the aircraft rolling forward slowly so you don't have to start from a full stop, but sometimes that isn't possible. (Delays at DCA & LGA??? Nah...) It's times like those that you're glad that they don't have light aircraft lined up behind you at these places... a two-seat Cessna won't do well with lots of jet blast!


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Is it possible to have a fully electric airliner?
Is it possible to have a fully electric airliner?
How much room would have to be sacrificed for a power bank in these aircraft to allow similar range to the current models (e.g., A320, 737, etc.)?
Would it shrink the passenger capacity by a lot? Or is the concern mainly having enough power to push such weight?

What do you mean by "electric"? If you want to replace jet engines by electric propulsion, you would end up with engines not optimised for the airframe cruise speed design, the need of electrical and hydraulic power generation (usually done by jet engines while in flight), ...

Since this wasn't closed, perhaps we need a respective question for every single aircraft model ever produced. I can write the bot, anyone got the API specs?

Well, to use the same airframe, you'd basically have to find a way to replace the fuel volume in the wings with battery volume, and batteries are somewhere around 15-20% of the power density of fuel, as the answers in this ASE post lay out pretty well.
So if you had an electric fan that made the required thrust, and somehow figured out how to replace all the fuel tanks with batteries, you'd probably have something, but only with about an hour's endurance, which wouldn't even make up the IFR reserve range requirements most of the time.  You would have to replace a lot of pax with batteries to get even a couple hours endurance, which would kind of kill the business case.
So that kind of concept is pretty much a dead end until battery power density starts to approach the level of kerosene, maybe 20 or 30 years from now unless some massive new development comes along.

And don't forget that a battery pack has far more mass per cubic meter than a fuel tank, ESPECIALLY when averaged out over the duration of the flight as the battery remains at the same mass throughout the flight while the fuel tank gets lighter as fuel is used up, making batteries even less efficient.

One hour with an heavier airplane, not to mention additional weight due to hydraulic power generation (an electric APU?), you hardly have time to get to cruise altitude and speed.

That just accounts for the cruise power. Another big issue would be the C-rate/power required during takeoff. Large C-rate and high density are inverse to each other, unfortunately.

An hour? That sounds really optimistic :D

IF. In 20-30 years IF some massive new development comes along, not unless. It will take 10 from development to mass production, and it took 20 from Li-Ion mass production to Tesla cars. Airplanes are a bit more complex and a bit tighter-regulated.

John K.s answer applies to lithium batteries. They're quite convenient in many ways, but they clearly don't work for this application.
Fuel cells on the other hand are more reasonable. A fuel cell produces electricity from fuel, such as hydrogen or ethanol. As such, it doesn't have the weight penalties of batteries. Additionally, this mostly solves the problem mentioned by jwenting. The fuel is still oxidized and therefore the plane loses weight in flight.

It also does not have most of the advantages of electric planes though, because it still releases carbon dioxide—hydrogen has a lot of energy for weight, but due to its very little density, too little for volume, so it is not practical and any fuel cell design is stuck with hydrocarbon fuel anyway. At best this can increase the efficiency a bit, not being a thermodynamic cycle.

I know this is an old question but I find this topic interesting and thought I'd contribute.
Why not an electric plane?  The YouTube channel Real Engineering answers that question here:

It's over 10 minutes long but they give a good summary of the problem in the first 2 minutes.  To cut that down even shorter, it is the energy density of the batteries we have today.
Why not fuel cells instead of batteries?  Fuel cells will get hot and need to be cooled.  The air needs to come in at a rate sufficient to supply the oxygen required.  The exhaust will likewise need a free flow into the air.  So, you have a very hot fuel cell, very hot exhaust, a big fan to cool the fuel cell, pump in air, and presumably propel the craft.  To assist in the air in and out while stationary a turbine can be placed on the exhaust to drive an inlet fan.  Question, what do we need the fuel cell for?  Right, to power the big fan at the front.  That brings more mass to the plane with a motor and then problems with the fuels that I'll get to later on.
The ability to "cut out the middleman" so to speak was discovered with piston engine development during World War II.  All sides of that conflict figured out that as piston engines grew the contribution of the engine exhaust to the thrust grew.  With a turbocharger required to get the most performance, especially at greater altitudes, the piston engine in the middle wasn't helping much.  By just dumping fuel into a combustion chamber, putting a turbine on the exhaust, and use that to drive a fan to feed the flames of the burning fuel, the exhaust alone could propel an airplane to high speeds and quite efficiently.  This efficiency over a propeller improved with greater speeds and altitudes.  Later on bypass fans and propellers driven by the turbine were added when speeds remained subsonic.
What's the goal of using an electric airplane?  Why bother when jet engines work so well?  Oh, right, to lower CO2 emissions.  We can use a biofuel for that.  But there is a problem with biofuel, as it is currently done this is an energy negative process.  We can improve this process but that comes with other problems.  Again, Real Engineering explains:

If corn ethanol is out, as is soybean oil, then what about hydrogen fuel?  Real Engineering has a video on this too:

While it is focused on cars much of the problems addressed comes in producing and storing the fuel. One problem pointed out is that producing hydrogen is an energy negative process.  This is not a deal killer as there is a benefit in being able to turn energy from the wind, sun, nuclear fission, or heat within the planet into a liquid fuel.  This means biofuels are not killed by being energy negative either, but by the need for land, fresh water, and labor that would be better spent on crops for food and clothing fiber.
What it comes down to is that the jet engine is just fine, it is the fuel that needs to change.  The most likely candidate is synthesized hydrocarbons.  These are drop in replacements for existing petroleum fuels and can be produced in a way that is a net carbon neutral.  Burning the fuel does release CO2 into the air but we know how to get that carbon back and build more hydrocarbon chains with carbon neutral energy.
In response to @MSalters comment about fuel cell heat I'll make some more observations on the practicality of a fuel cell airplane.
I'm not claiming that removing the heat from a fuel cell is a problem, only that it must be done.  As MSalters points out we learned a lot about how to build efficient and high flying aircraft in the last 100 years.  The Meredith Effect tells us how to get useful thrust from heat sources on aircraft.  We know from using piston engines at high altitudes that a turbo charger is an excellent way to get the same performance at high altitudes as at sea level.
Combine the Meredith Effect with a turbocharger and the fuel cell is just a combustion chamber for a jet engine.  If someone where to go through several iterations of optimizing thrust from the Meredith Effect and the fuel cell powering a fan or propeller then could we see the fuel cell optimized out?  My guess is that is exactly what would happen.
Does someone want to argue that fuel cells can do better than a jet engine?  A jet engine can get about 40% efficiency.  We can get the same from a fuel cell... at sea level.  What happens in thinner air?  The fuel cell will need something to pump in the air, and something to remove the heat.  Again a turbocharger is good for this.  That turbocharger will take some of that energy from the fuel cell.  If we run the fuel cell hot then the turbocharger gets more efficient.  Will higher temperatures lower the fuel cell efficiency?  Perhaps, but it could be made up by a more efficient turbocharger that feeds the fuel cell air.
What if we go further in sacrificing fuel cell efficiency to get more from the Meredith Effect, and better turbo charger performance?  Do this a few more times and the fuel cell isn't in the picture any more.
One reason people like a fuel cell is because it can run on "green hydrogen", hydrogen from carbon free energy.  Well, a jet engine can run on hydrogen too.  If the fuel is "blue hydrogen", hydrogen from fossil fuels, then it's no more "green" than a jet engine burning kerosene.  We know how to run an internal combustion engine from hydrogen so unless we can get significant gains in efficiency from the fuel cell, which is doubtful, then the fuel cell carries no benefit.
It may be possible to build a fully electric airplane but it's not likely to be any better in costs or CO2 emissions than a jet running on "green" synthesized fuels of some kind.

The "fuel cell runs hot and cooling is a problem" sounds a bit dodgy. The Meredith effect means that this can actually produce thrust. That's WW2 era technology


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Who does ATC call when a plane disappears with no response?
Do they just call 911? Or is there some special unit that’s specifically trained around disasters and rescue?

Most countries have established some sort of Rescue Coordination Centre responsible for search and rescue operations in case an aircraft or ship goes missing. The RCC typically has direct access to various SAR resources such as helicopters. They can also call in local emergency teams (police, firefighting, ambulances etc.)
How exactly the RCC is notified of an incident can be different. It may be through a normal emergency telephone number (such as 911) or via some direct communication channel.

+1 - The UK version of this is the D & D cell here: https://nats.aero/blog/2014/08/distress-diversion/

In the US, the ARTCC where the incident occurs acts as the focal point for search and rescue operations. They work directly with the US Air Force Rescue Coordination Center, local, state, and Federal law enforcement (if necessary), and the Civil Air Patrol during search operations.


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Would a 737 pilot use flaps in nose dive?
Since flaps help lift the plane, would they deploy flaps if the plane was nosediving? And what would they do if the back pressure was too much? I know speed increases lift, but can full throttle make the plane difficult to level out?

Are you talking about an accidental nosedive?

Yes. Mainly recovering from a nosedive.

By nose dive, do you mean controlled emergency descent (as in depressurisation incident) or uncontrolled nose down attitude? (or something else?)

About the only way you can have a spontaneous "nosedive" is for the autopilot or stab trim system to runaway in the Nose Down direction.  Nose Down = higher speed; the trim speed is being increased and the plane pitches over to maintain it.  On the 737 flaps induce a nose down pitching moment increasing trim speed further (setting aside speed limits on flap extension).

No, flaps are never used during a nose dive.
We need to distinguish between two scenarios:

Intentional nose dive: this is actually called a rapid descent maneuver. The FCTM (Flight Crew Training Manual) has a whole section dedicated to it. The general procedure looks like this:

From the Boeing 737 NG FCTM (7.5 Maneuvers - Rapid Descent - Level Change (LVL CHG)):

Because of airspeed and altitude protection and reduced crew workload, use of the
  autopilot with LVL CHG mode is the recommended technique for rapid descents.
  Use of the V/S mode is not recommended.
Initiate a turn, if required, using HDG SEL. Set a lower altitude in the altitude
  window. Select LVL CHG, close the thrust levers and smoothly extend the
  speedbrakes. Autothrottles should be left engaged. The airplane pitches down
  smoothly while the thrust levers retard to idle. Adjust the speed as needed and
  ensure the altitude window is correctly set for the level off. During descent, the
  IAS/MACH speed window changes from MACH to IAS at approximately 300
  KIAS. Manually reset to VMO as needed.
When approaching the target altitude, ensure the altitude is set in the MCP altitude
  select window. Altitude capture engages automatically. Adjusting the command
  speed to approximately LRC or 300 knots before level-off aids in smoothly
  transitioning to level flight. The pitch mode then controls altitude and the thrust
  levers increase to hold speed. Smoothly return the speedbrake lever to the down
  detent during the level off maneuver.
When descending with the autopilot engaged and the speedbrakes extended at
  speeds near VMO/MMO, the airspeed may momentarily increase to above
  VMO/MMO if the speedbrakes are retracted quickly. To avoid this condition,
  smoothly and slowly retract the speedbrakes to allow the autopilot sufficient time
  to adjust the pitch attitude to maintain the airspeed within limits.
When the speedbrakes are retracted during altitude capture near VMO/MMO, a
  momentary overspeed condition may also occur. This is because the autopilot
  captures the selected altitude smoothly by maintaining a fixed path while the
  thrust is at or near idle. To avoid this condition, it may be necessary to reduce the
  selected speed and/or descent rate before altitude capture or reduce the selected
  speed and delay speedbrake retraction until after level off is complete.

In case a higher descent rate or lower descent airspeed is required, the landing gear can be extended additionally to the speedbrake, but flaps are never mentioned:

Landing Gear Extended Descent
The rapid descent is normally made with the landing gear up. However, when
  structural integrity is in doubt and airspeed must be limited, extension of the
  landing gear may provide a more satisfactory rate of descent.
If the landing gear is to be used during the descent, comply with the landing gear
  placard speeds.

Accidental nose dive: this would fall under the general term of upset. The recommended procedure is described in the FCTM (7.26 Maneuvers - Upset Recovery):

Nose Low, Wings Level
In a situation where the airplane pitch attitude is unintentionally more than 10°
  nose low and going lower, the airspeed is increasing rapidly. A pilot would likely
  reduce thrust and extend the speedbrakes. Thrust reduction causes an additional
  nose-down pitching moment. Speedbrake extension causes a nose-up pitching
  moment, an increase in drag, and a decrease in lift for the same angle of attack. At
  airspeeds well above VMO/MMO, the ability to command a nose-up pitch rate
  with elevator may be reduced because of the extreme aerodynamic loads on the
  elevator.
Again, it is necessary to maneuver the airplane's flight path back toward the
  horizon. At moderate pitch attitudes, applying nose-up elevator, reducing thrust,
  and extending speedbrakes, if necessary, changes the pitch attitude to a desired
  range. At extremely low pitch attitudes and high airspeeds (well above
  VMO/MMO), nose-up elevator and nose-up trim may be required to establish a
  nose-up pitch rate.

Also here, flaps are not mentioned, so only speedbrakes should be used to increase drag (and increase the nose-up pitching moment).

How does a reduction in thrust help if it induces a pitch-down moment? I thought that's the opposite of what you want. Or is it just mentioned as a consequence of reducing thrust you should keep in mind here?

@geisterfurz007 Yes, reducing thrust is what you naturally do when your airspeed increases rapidly (which is unavoidable when nose diving) and here the pilot is just reminded of the thrust-pitch-coupling acting in the wrong direction for recovery. The effect of the speedbrakes should be much larger though.

@geisterfurz007: It pitches you down, but it also helps keep you from speeding up too much during the descent (going excessively fast may void the warranty on the airplane and its contents).

Looking at the Performance Limitations of the Boeing 737 (page 3),  we see that the Flap Limit Speeds are
+================+==============+
| Flap Position  | Limit Speed  |
|                |      (KIAS)  |
+================+==============+
| 1              | 250          |
+----------------+--------------+
| 2              | 250          |
+----------------+--------------+
| 5              | 250          |
+----------------+--------------+
| 10             | 210          |
+----------------+--------------+
| 15             | 195          |
+----------------+--------------+
| 25             | 170          |
+----------------+--------------+
| 30             | 165          |
+----------------+--------------+
| 40             | 156          |
+----------------+--------------+

This behavior is the same in basically all aircraft as far as I know. With flaps down, the wings need lower loads than when "clean". So deploying flaps when in a dive can be catastrophic.
For an example of what happens when deploying flaps/slats at high speed, see the accident of Austral 2553.


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Will the 737 Max 10 have MCAS?
With the fuselage plugs forward of the wing, would this mean the engines are closer to CG, therefore no need for MCAS?

It looks like the 737 MAX 10 will also have MCAS:

The Boeing MAX 10 will contain an upgraded version of a flight handling system that has been seen as a key factor in both crashes involving casualties of 346 people.
The mechanism - the Maneuvering Characteristics Augmentation System (MCAS) - has been tweaked to give the pilot more control. But regulators, including the Federal Aviation Administration (FAA), have yet to sign off on the changes.
"I'm honoured to take this aeroplane on its first flight and show the world what you've put your heart and soul into," 737 chief pilot Jennifer Henderson told the employees gathered for the debut of the first 737 MAX 10 at the company's Renton, Washington factory.

(aviationpros.com, emphasis mine)
As far as I could find, there is no official statement from Boeing on this. They only say

MCAS, or Maneuvering Characteristics Augmentation System, is a flight control law implemented on the 737 MAX to provide consistent aircraft handling characteristics at elevated angles of attack in certain unusual flight conditions only.

(boeing.com)
without distinguishing between the different variants. Their 737 MAX 10 page does not include any details on MCAS.

The fuselage length is immaterial. The problem of the Max series relates to the positions of the engines versus the wing, and their aerodynamic interference near the at high alpha. The amount of fuselage ahead of the wing or behind the wing is not a major factor here.

The MAX 10 fuselage is also lengthened behind the wing:

In October 2016, Boeing's board of directors granted authority to offer the stretched variant with two extra fuselage sections forward and aft with a 3,100 nautical miles (3,600 mi; 5,700 km) range reduced from 3,300 nautical miles (3,800 mi; 6,100 km) of the -9.

Wikipedia: Boeing 737 MAX 10
Basically the center of gravity of MAX 7,8,9 and 10 is in the same location (range) in respect to the wing, or mean aerodynamic chord (MAC) of the wing to be more precise. As the engines are essentially the same in all MAX variants, and so is the location of them, the engine location from CoG is pretty much precisely the same.
The need for MCAS cannot be solely determined by CoG of MAX 10, as the longer fuselage may have some other effect on stability, but my personal guess is, some kind of maneuvering augmentation is necessary.

Wasn’t the entire point of MCAS to make the aircraft “feel” like the NG? Due to the engine configuration they had “easier stick forces” and therefore needed MCAS, so if the engines are not placed forward and up, then there’s no need for it?

But the engines on all MAX versions are "forward and up" @Firefighter1

i apologize, thanks for that. If the Max 10 is the Max 9 with a longer fuselage, wouldn’t that cross out the engine configuration? Doesn’t the new landing gear have a role in this as well?

@Firefighter1 The new landing gear has no effect on engine location. It could have, but Bojong didn't want to invest in designing a new engine mount just for MAX 10. To be fair, that's understandable, saving on MCAS was not.

wouldn't the longer fuselage mean that the proportional difference between cg and engine location is less?

There is nothing proportional in distance from  CoG. CoG is a single point, not a vector. Longer fuselage does have higher inertia so the relative effect of the engine is smaller if that is what you mean @Abdullah ?

The problem  MCAS was supposed to address was not related to inertia, it was about aerodynamics.

@Jpe61 yes, that inertia effect was what i meant, i guess


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Why do small jets usually have one low flap setting?
For example, the CRJ has a flap setting of 0, 8, 20, 30, and 45 degrees.
The Learjet has similar features across their models, as far as I can see which is 0, 8, 20, and 40 degrees
Why do smaller jets have one low flap setting? Why not have 0, 8, 15, 20, 40? Comparing to larger aircraft like the 737, they have a flap setting that captures just about every degree you can imagine.

The A380 only has five flap positions: UP, 1(+F), 2, 3, FULL
It's a design philosophy, keep it simple and easy to use...vs. full flexibility.
In a 737 the flap positions 2, 10 and 20 are rarely used at all. Mostly flap 1, 5, 15, 30 or 40...
It has pretty much nothing to do with aircraft size

@Jan And to expand on that, the small Grob 115 which I sometimes fly has an electric flap with near-infinite settings! And, like you say, everybody just uses a couple of pre-marked points.

The provision of lots of flaps settings is motivated in part by the desire to provide as many profile optimizations as possible. Generally, the less the flap extension for takeoff, the more efficiency you have in a departure plus better engine failure performance, but you need the longest runway, so you would use the least extension allowable for a given runway.
The CRJ was originally certified without an 8 degree flaps setting, and it was added as an option a year or so into production.  In general, you will always use Flaps 8, unless conditions require Flaps 20 (shorter runway).
It can create a trap for the CRJ because if you are departing an airport where 20 is required to meet departure performace requirements, and you set Flaps 8 by mistake, there is no Takeoff Configuration Warning mode to warn you you're at the wrong takeoff flap setting (only a warning for 0, 30 and 45... it can't know which 8/20 TO setting you actually want) and you can take off with insufficient flap extension and get into a bit of trouble when you rotate at the Flaps 20 Vr and you don't lift off.  When departing a short field that required Flaps 20, you had to be extra careful to make sure Flaps 20 was selected.

What's the speed difference between VR at flap 8 vs. VR with flap 20? An example would be nice

It's somewhere around 10-15 kt IIRC but it's been almost 10 years and I'll have to try to dig up an old CRJ200 speed book.


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Can a commercial airline pilot, flying either A320 or B737, charge people for a flight in their own personal Cessna 172?
Or would they have to be some registered business for the industry?

Please specify a country, as laws are different from place to place.

I think this is too broad. For example if he were to pay his own seat, and the charges only covered the cost of the aircraft, fuel, and oil, and he was not "holding out", it may be legal. The faa has a very broad definition of compensation which may not involve the exchange of money. Generally though the consensus in the faa world is no. Add a country and I can give an answer.

Presumably you mean either part 121 air carrier or part 135 charter operations, both of which have a lot of requirements beyond just holding an ATP (or in small piston 135 cases commercial) pilot certificate.  Otherwise this would only work as limited cost sharing under part 91.  Those requirements would be much more about substance than business structure; there might be some rules there but likely anyone doing this would have some sort of corporation as there are many non-flight reasons that would make sense anyway.


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Does the FAA dictate that bridges are closed for the Thunder Over Louisville airshow event?
A big tradition here in Louisville is "Thunder Over Louisville". This starts the celebration for the Kentucky Derby. 'Thunder' is an airshow, fireworks, fair, concerts, and a nice day out along the river. This event leads to the closure of bridges over the Ohio River. Some closures are brief, such as I-65. Others are days long because fireworks and other aspects of the theatrics are positioned there.
We have a new pedestrian bridge called "The Big Four Bridge" which was opened very recently. This bridge is closed despite being a very obvious attraction to attendees and it can ease car traffic by allowing foot traffic across the river. There are many notices that this bridge is closed, but none of them cite the authority that closed the bridge.
Does the FAA hold sufficient authority to close bridges, roadways, or other locations for an airshow?
If so, what resources should I use to locate these closure notices?
This question is simply a curiosity. There are many logical reasons for the 'Thunder' organizers, local police, state police, and the FAA to close the pedestrian bridge. I want to learn more about what authority the FAA specifically would have in this matter just for the sake of learning.

when it's an event run by the local authorities it's them that will decide which bridge to close based on requirements of the participants (which may or may not include the FAA not wanting to blow people off the bridge with to jetblast).

Interesting question, especially since I live in Louisville. Unfortunately the weather forecast for Saturday is terrible :-(

I imagine the airshow must be really loud...

@Pondlife - Might be worth going, the rain should slack off later in the day. It'll make for a lousy airshow, but thinner crowds and the fireworks are different under a cloud layer.

@kevin - I don't think so. It's loud from the crowds but I don't recall the airshow noise being any better or worse than say the Dayton airshow. The view is spectacular though, the aircraft almost seem like a promotional film with the various city sights as a backdrop and the festival atmosphere.

I'm confused. The bridge in question is new-ish as a pedestrian bridge, it was built as a railroad bridge in 1895 ("Big Four" was the nickname of the Cleveland, Cincinnati, Chicago and St. Louis Railway). It opened to pedestrians in 2013. So how did this suddenly become an issue?

@david it opened partially in 2013. The ramp on the Indiana side wasn't done until 2015 so you could go on the bridge but not get to the other side.

@Freiheit OK, but that doesn't seem to affect aircraft very much.

The FAA has no authority over roads, bridges or any other public roads. Usually, it's the the event organizer who's responsible for requesting and coordinating road closures; think of triathlons, parades etc. And even without the FAA, there are very good reasons for the local police to close the bridges: rubbernecking and accidents caused by distracted drivers; keeping people safe when fireworks are set off from the bridges and so on.
But, at least in theory the FAA could indirectly require road closures as part of an airshow waiver.
Most airshows require a waiver, i.e. permission from the FAA to 'ignore' certain regulations. The list of regulations that can be waived is in 14 CFR 91.905 and you can immediately see why some of them would be waived for an airshow. These ones in particular seem very relevant:

91.111   Operating near other aircraft.
  91.117   Aircraft speed.
  91.119   Minimum safe altitudes: General.
  91.303   Aerobatic flights.

The full instructions for issuing a waiver are long and detailed but there are lots of requirements to ensure minimum distance between aircraft and spectators, and to ensure that the energy vectors of aerobatic maneuvers are not directed towards crowds.
I haven't been to Thunder yet so I don't know to what extent the aircraft actually maneuver vs. flying in stable formation down the river. But, it's at least very plausible that the FAA has issued an airshow waiver requiring a minimum distance from spectators that can only be guaranteed if some of the bridges are closed. And, if the park area around River Road is the main spectator area, then any aerobatic maneuvers would have to direct their energy vectors along the river, i.e. towards the bridges. That could require the airshow organizers to request that the bridges be closed.
Unfortunately I couldn't find out if airshow waivers are public or not (a quick search on faa.gov didn't find any) so I don't know if it's possible to check which FAA regulations have been waived for Thunder, or what conditions they placed on the organizers.

I saw the Red Bull Air Race in Detroit where it's held above the Detroit River, across which is Windsor, Canada. I wonder if 91.707 Flights between Mexico or Canada and the United States was waived for that :P

The FAA definitely has problems with the bridges. They don't have authority to close bridges, but they do have authority to refuse the waiver contingent upon things they feel are not safe.
It started while the bridge was under construction. They almost didn't approve the waiver due to the cranes. Apparently they were satisfied when the fire dept was able to put flags on them to make them more visible.
Last year they wouldn't approve a "box" big enough for the USAF Thunderbirds to do their maneuvers. And it seems that now the bridge is there they probably won't ever approve enough room for the T-Birds.
So, it would appear that the bridge closure is a compromise with the FAA.

It seems that, according to this accepted answer the military can ignore, to a certain extent, FAA regulations. It's too bad they can't/won't do so in this case...

@FreeMan I suppose at a technical level the military could change their rules but the T-Birds specify that they need an FAA waiver. In this document they indicate specifically what rules they need waived and all the airspace and ground accommodations they require. They're pretty particular about such things

As they say, FAA regulations are written in blood. FAA regulations in relation to airshows, in particular, are written in lots of blood, a significant portion of which was spilled by military display teams (think of Ramstein, for example). I guess it would be pretty bad PR if they just said "hey, you know all those rule you created because of all those people that were killed by military airshows? We're just gonna ignore those, since we're the military."

OK, valid points, guys. Just disappointing for those in attendance. Fortunately, Dayton isn't too far from here, so there should always be a good air show available.

@FreeMan I wonder if the city took that into consideration before building that bridge. My guess is they had no idea. They were probably thinking, "this will be an awesome place to watch the air show from."

No, the FAA does not have the authority to close a bridge, roadway, or other general public item outside of an airport or airspace.
The appropriate regulations are 14 CFR 91.303

Aerobatic flight.
No person may operate an aircraft in aerobatic flight--
  (a) Over any congested area of a city, town, or settlement;
  (b) Over an open air assembly of persons;
  (c) Within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport;
  (d) Within 4 nautical miles of the center line of any Federal airway;
  (e) Below an altitude of 1,500 feet above the surface; or
  (f) When flight visibility is less than 3 statute miles.
  For the purposes of this section, aerobatic flight means an intentional maneuver involving an abrupt change in an aircraft's attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight.

I've highlighted the appropriate parts of the regulation that would require a bridge to be closed, however the FAA does not actually do the closing. The show organizers need to coordinate with local/state officials (depending on if it is a local or state controlled road) to have the correct area's closed off so that the show does not violate the regulations.
There is a waiver process as noted in Pondlife's answer but I don't believe the FAA will issue waivers for (a) and (b). The most usual waiver is probably for (c) and (e).
So, in short, the FAA cannot close the roads, however it can regulate the airshow which would require the organizers to abide by the FAR's. How they close it is up to them, but it is the organizers responsibility to ensure that the FAR's are not violated.

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text:
What are magnetrons installed on aircraft used for?
I'm interested in characterizing the radio signatures of magnetrons that appear to be installed in most large aircraft, some examples appearing on this list:
http://www.mpdcomponents.com/pdfs/FAA-PMA.pdf
My understanding is that these magnetrons were the first form of radar, but other technologies have largely supplanted them. However, they still seem to appear in the parts lists of modern Boeing and Airbus jumbo jets.
My question is what are these magnetrons used for, and when they are used, how they are used? Do pilots still use these regularly?

Hm, neither of the aircraft models in the list you link to seem to be recent designs. It tops out at 747-200, 737-200, Learjet 36 and so forth. I didn't see one newer than 30 years; most are from the 1970s.

First thing that comes to my mind is for heating meals in the galleys.

@HenningMakholm Thanks! Honestly the parts list I posted was just from some Google sleuthing, and I don't know if more modern craft have these installed. How many 1970s-era craft are still in operation?

@RobVermeulen My understanding is that food is typically heated in convection ovens on aircraft, microwaves are specifically avoided because of the potential for RFI.

Guillochon...the magnetrons I discussed below were installed in OLD radar systems.  Even though the radar systems were upgraded numerous times, the magnetron was still a part of the receiver-transmitter installed on Boeing's KC-135 (delivery from Boeing ended in 1966).  That particular radar system was removed and replaced with a solid state color weather radar system on the KC-135.  The Search and Weather Radar I mentioned below is still installed on some C-130 aircraft.  Many U.S. military aircraft manufactured in the 1960s are still in operation.  Google C-135, C-130, and B-52 for specifics

The magnetron is a high-powered vacuum tube, that works as self-excited microwave oscillator. They are used mainly in radar transmitters as either pulsed or cw oscillators at frequencies. In (civil) aircraft, they are mostly used in weather radars.
They have relatively simple construction but have been replaced in almost all aircraft due to their disadvantages:

They can usually work only on a constructively fixed frequency.
They have poor reliability.
They have high power consumption and have noise issues.
They have finite life, considerably lesser than solid state devices.

Most of the aircraft operating today use solid state devices in their Radars. It may be still used in some older aircraft and helicopters, but they are becoming increasingly rare.
Weather radars are regularly used by pilots to detect the weather conditions in front of them. According to Airbus Flight Operations Briefing Notes: Optimum Use of the Weather Radar The weather radar only detects:

Rainfall
Wet hail and wet turbulence
Ice crystals, dry hail and dry snow. However, these three elements give small reflections compared to water droplets.

It does not detect clouds, fog or clear air turbulence.
Most of the aircraft in the list were designed 25+ years ago and have (mostly) switched over to solid state devices. Aircrafts are rarely used after 30 years as maintenance becomes expensive.
However magnetrons are still used in some aircraft due to their simple construction and high power output. For example, the WU-880 Radar Receiver Transmitter Antenna in Honeywell Primus 880 radar used in Falcon 2000EX uses magnetron.
Note: Almost all commercial aircraft use convection ovens to heat food (they won't have aluminum foils if they microwave ovens were being used); however, microwave ovens are available for aircraft and are used in some executive aircraft.

Thanks very much for the thorough answer. Are these magnetrons continuously powered, or are they only switched on in the presence of inclement weather? Do you have any idea what the magnetron signal would look like to a receiver on the ground? It would be great to contact you directly if you have expertise on these devices.

Didn't transponders originally use magnetrons?

@Guillochon The magnetron (weather radar) is usually used according to requirement. It is rarely powered on continuously.  A magnetron (usually) produces radio waves. To a receiver in ground, the signal would be similar to any other radio source, for. e.g. a radar, though the power would be very less.

@rbp Yes. They did use magnetrons initially, though this has reduced since.

@aeroalias Thanks again for the useful info!

Aeroalias provided a great answer!  Additionally, don't think of a magnetron as a component installed on an aircraft, think of it as a component installed within a black box (in this case, a transmitter, that's part of a system installed on an aircraft).
There are multiple magnetrons listed within the link you provided above.  The first part number, 257-0261-020, is the original part number installed within a Collins black box.  The next two paragraphs are a cut and paste from the MPD Components, Inc.'s Products website (http://www.mpdcomponents.com/products.htm):

MPD Components, Inc. is a diverse manufacturer capable of providing
  total solutions from ceramic insulators to complete RF assemblies. Our
  background and expertise is in applied electronics, microwave RF,
  Vacuum Electron Devices (VED's) and ceramic-to-metal sealing.
Magnetrons (VED's)--MPD offers positive and negative pulse magnetrons.
  Our magnetrons are for pulse applications with the majority being used
  for airborne weather radar and beacon magnetrons. Typical peak powers
  run from a minimum of 1.3 kW to 10 kW for Honeywell, Sperry, RCA,
  Bendix, King, AlliedSignal and Narco radars. Several magnetrons have
  FAA-PMA applications.

You later asked if the transmitter is continuously powered and the technical answer is, "yes...as long as the system is turned on."  That might seem like a cop-out answer, but it's true.  I "think" you meant to ask, "Does the magnetron continuously transmit?"  Without knowing the specific system the magnetron is installed, I don't think anyone can definitively answer how long it transmits, but it wouldn't be continuous or it would overheat.  For example, let's say this magnetron is installed in an aircraft radar system--the duty cycle (amount of transmission versus the amount of non-transmission) is going to vary based on what the radar system is designed to display (mode and range).  When the system is turned on and placed in a transmitting mode (not "standby"), the system will transmit a pulse, long enough to send the pulse.  Then the transmitter will shut down and the receiver circuits will open.  This prevents the receiver from taking in a high-powered signal (a received echo is very small).  For a pulse radar system, how many times the system transmits is called the "PRF" (Pulse Repetition Frequency or Pulse Recurring Frequency)--measured in pulses per second--and could be hundreds or thousands of times per second (depending again on the purpose of the particular radar system.
One last thing, somebody asked if transponders use magnetrons.  I think the answer is "No", but there could be a transponder system that used them.  I believe most used a klystron.  Regardless of what generates the power of the transmission, what I wanted to say is that a transponder does not transmit the way I described above.  For example, an IFF transponder could be set to "normal" mode, operate correctly, and not transmit one time during flight.  How?  Because a transponder doesn't initiate the process like a radar system.  With transponders, an interrogator (airborne or ground system) initiates the process with a "Who are you?" type of signal.  "If" the airborne system receives a valid interrogation, the system will transmit a "This is who I am!" type of reply...otherwise, the system will stay in receive mode until it receives a valid interrogation.  If an air traffic control radar system or an airborne system believes they're properly interrogating, but there's no reply, they can use a communication system to verbally request the pilot to "identify"...and the pilot flip a switch, forcing the system to electronically transmit.  Again, what I described is "normal" IFF operation.  In an emergency (fire, hijacking, etc.), a pilot can select an "emergency" mode and the system will automatically start transmitting (squawking) the emergency code.

Guillochon, I'm new here, but I can already see this web site is going to be a true test of my ADHD!  I went to the help link because somebody provided an answer and I was wondering if it's possible to send a private message or if a general chat is allowed within a question.  In any case, magnetrons (I don't know specific part numbers) were components in an RT-289 (numerous versions) as part of the Search and Weather Radar System (AN/APN-59) installed in C-135 and C-130 (possibly other aircraft as well).  The KC-135 has since upgraded their system, but some C-130s still use this system.

Magnetrons are still used in most All general aviation radars. Echoes are returned from targets that are wet. Ice returns only one fifth of water droplets of a similar size. air carrier aircraft use solid state radars because they are capable of coherence. These coherent radars are capable of predictive wind shear capability, which is why airlines no longer use magnetrons.

authors: Филип Видиновски

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If this is not a Lippisch L-13, what is it?
The image comes from a 1956 Nestle, a chocolate maker, sticker album. 'Maravillas del Universo', serie 1. Chapter has 3 pages, and is entitled: 'The sound barrier', signed by the woman test pilot: Jacqueline Cochran. It indicates it's a Lippisch L-13, but it's not, Lippisch L-13 was a rearwards swept Delta design, with a thick Vertical Fin that included the pilot's cabin, it was tested as a glider. Final version had to use a Ramjet, fueled by burning coal in a rotating basket. YouTube video link.

Who says it is supposed to be any real-world aircraft? It looks pretty sci-fi to me....

No control surfaces, no (obvious) propulsion system - I doubt anything like this has ever flown more than a ballistic parabola, if it was built at all.

Nestlé seems to mix more things than cacao and sugar. Jacqueline Cochran was American, and the first woman to break the sound barrier on May 18, 1953. It was on a Canadair F-86 Sabre at Edwards Air Force Base, California. In doing that, she succeeded as the fastest woman to Jacqueline Auriol, a French pilot (who regained her title later).

It might actually be Lippisch L-13... as drawn by someone who knows nothing about aircraft based on a verbal description.

The DM-1, the glider  mockup for the Lippisch P13 was subject to extensive testing in the US as early as 1947, so, it can be said with all certainty that the Lippisch Delta design was known when the Album chapter was written, to which extent it was under confidentiality, I don't know, but the flying machine in the stamp has little connection to L-13/P13 a and b, besides somebody attributed it to Lippisch.  http://www.dtic.mil/dtic/tr/fulltext/u2/a801410.pdf

To mins: sorry, when I first wrote the question, I misinterpreted from her name and surname, that Jacqueline Cochran was French, whe she was fully American, it wasn't the Nestle mistake, but mine

Thanks for the language correction, but please, let myself, and just me, change my writings, I gave no one permit for this. I requested aviation info, not a Toefler. You can have a detailed anaylisis of the true Lippisch L-13 in https://airandspace.si.edu/multimedia-gallery/11422hjpg there are 4 documents in the National Air and Space Museum about DM-1, also: https://ntrs.nasa.gov/search.jsp?R=19930093794

Alexander Lippisch did develop a similar-looking wind tunnel model, see photo. According to his Errinerungen (memoirs), Page 218, this was in 1943 and it was tested in 1944. Dan Sharp; Secret Projects of the Luftwaffe: Vol. 1 Jet Fighters 1939-1945 (Mortons 2020) shows a couple of photos on Page 219 and says that it marked the start of his delta-winged P.12/P.13 project, including the DM-1 glider which was actually built and flown. But this early wind tunnel model had only a thin central spine, with no cockpit and, like all his delta aeroplanes, was designed to fly apex foremost.

The illustration on the sticker or card is, as you note, back to front. Consequently its supersonic performance would be appalling. It is probably based on a photo of the model, with its identification based on remarks about the P.13 (or Projekt 13), but is otherwise total fantasy. Presumably there is no suggestion that the author of the article actually flew it.

Do you have a serial number or name of the Wind Tunnel tested A Lippisch concept you cite? This may help looking for it. About the 'Inverted Delta' Lippisch designs, what I'm aware is about his Ground Effect machines, as X-112. Jacqueline Cochran was author of text in album section including the Sticker above, I don't think she ever flew any Lippisch airplane. Thanks. Blessings +

In his* Erinnerungen* (Memoirs), on Page 218 he gives a photo of it with the caption "Modell für einen Überschallflügel, der schon 1943 entworfen, aber erst 1944 vermessen wurde". It appears to have had no other known identification. Of course the GEV was not intended to fly as such, it was by definition stuck in ground effect. Nor was it a "Lippisch delta" as any aeroplane designer uses the term, any similarity is only skin deep.

According to the air force via wayback machine Jacqueline "Jackie" Cochran born Bessie Lee Pittman was the first woman to break the sound barrier in an F-86 Sabre Jet in 1953. Cochran retired from the Reserve in 1970 as a colonel. She received numerous awards, including a Legion of Merit.
The Lippisch aircraft was designed in late 1944 and never built.
This is a case of mixed up facts.

Why the downvote? All information provided is correct!

I'm not the downvoter, but my guess is that the reason lays in your first sentence: this is not a direct answer to the question "what aircraft might this be?"

Yes, it does provide an answer. The answer has two parts. It refutes the statement from the mentioned sticker album and it does provide the answer, that the pictured plane is not a Lippisch 13.

@mike we already know what it is not, we are looking for what it is.

I know this is not a Lippisch L-13, the question is: what is this? Jacqueline Cochran has a French surname, but she's not French, but American,
I corrected this silly mistake before. Anyone having data about this inverted Delta wing, no obvious propulsion system device?

It's nothing. An artistic drawing from a sticker album.

To Mike: Which Lippish aircraft you say was never built? The L-13 was built, and flown as a glider, see YouTube, in the version with long cylinder nose, prepared for the Coal burning Ramjet, the previous version, with no air entry, was seized and tested at Langley, with interesting modifications that improved a lot the results, the Airbus 'Sagitta' drone looks very close to the DM-1 version tested at Langley

@mike That comment above seems like the right answer to me: "It's nothing. An artistic drawing from a sticker album."

Searching  'Espacenet' patent database, I found a flying machine by Alexander Lippisch, CA 556254, 1958, Rotor Aircraft, that is what most resembles the sticker image. Blessings +


text:
What's the shape and place of the tip vortex in a propeller, depending on propeller sense of turning?
If the propeller vortex is placed and has changing features depending on the propeller sense of turning, both in traction and pusher configuration, knowing about this may have an interest for the design of multi-propeller airplanes.

I'm not completely sure what you're asking, but this question might help

I too am unsure exactly what your question is but propeller blades shed vortices at the tips just like wings and rotor blades. This vortices and their paths can be seen when the weather conditions are right as in this photograph. (I don't own this image)

You can find many more of these types of images with a quick google search. The vortices roughly follow the advance ratio of the propeller at the moment they form. There would be little difference to the formation of vortices for push or pull configuration.


text:
Advantages of inverted Delta, straight leading edge?
The advantages and features of a Delta wing have been very well described here, but this arrangement of an 'Inverted Delta' differs; also, it would be good knowing more about performance of a Canard foreplane with an ordinary and inverted Delta wing.


text:
What are some examples of pilot error with criminal negligence?
I’m having a hard time understanding why pilot error technically can’t be criminal negligence all the time? So I’m curious to find out some examples of this exact scenario, and how investigators determine if ones negligence is punishable by law.

This is certainly very related to aviation, but it seems like more of a legal question to me and you may get a better answer on law.SE.

Accident investigators do not apportion blame, they only serve to determine cause. Moreover, the Convention on International Civil Aviation stipulates that accident investigation reports cannot be used in a court of law to apportion blame. Therefore, to bring a case of criminal negligence would require a very significant technical investigation, independent and separate from the official accident investigation, to produce enough evidence to stand any chance in a coutt of law.

Mistakes made in good faith (u just blew what you thought was a reasonable decision, or a situation is beyond your ability though you're trying to do your best) are not generally criminal in Common Law legal systems. If they were, everybody would hide their mistakes, and a lot of people would avoid doing the activity in the first place. Go to places like China and Russia, and pilots can go to jail for good faith mistakes (I've seen Chinese authorities throw maintenance directors in jail for screwups of their staff). Result: incidents don't get reported, and mistakes are hidden at all costs.

Searching google for “Pilot negligent homicide” returns quite a few results.

Most countries will not prosecute pilots for accidents with good reason - the safety system depends on people being open and honest about their actions, so as to ensure someone else does not repeat them. Investigation agencies like the NTSB make it clear that their reports are not intended to assign blame, and so typically cannot be used in court for that purpose.
Pilot convictions for airliner crashes are quite rare but I can think of 2:

Garuda flight 200, where the captain landed 100kts too fast ignoring dozens of warnings, killing 21
Air France 296, where the captain on a display flight flew much too low and too slow, killing 3. France is a slightly different situation however, as every fatal accident automatically triggers a criminal (technically 'judicial') investigation alongside the safety investigation by the BEA.
Tuninter 1153, where after fuel exhaustion the pilot judged that he did not have glide distance to make an airport and ditched in the Mediterranean resulting in 16 fatalities. The captain was convicted in an Italian court of manslaughter and was sentenced to 10 years. The first officer and the chief operating officer of the airline also received prison sentences.

There are some more examples from the General Aviation world (light aircraft), where you don't necessarily have the same professionalism and certainly not the same oversight and standards from an airline, but the principle of refraining from criminal proceedings remains the same.

I added another entry to your answer.

In the US, negligence would imply willfulness. Errors and accidents don’t imply willfulness nor negligence. That’s the difference between a death caused by an automobile traffic accident due to weather and one caused by a drunk driver. The latter is criminally punishable. The willfulness to do something wrong or not do something right is negligence. Making a decision that an average person would consider reasonable should not be prosecuted. Even if it is the wrong one.
The converse of making a reasonable decision in the case of flying would be to willingly fly the aircraft in a manner beyond the pilots capability or legal competency. If the pilot is not certificated and current, or flying the aircraft into a situation for which it is not certificated could be considered as negligent. The pilot had to do so due to an emergency, that would be a different story.
The same is true regarding intent. If your intent was to break a law, rule, or regulation (even if you did not know there was a law, rule, or regulation regarding your actions), that is criminal. A prosecutor or FAA official can even argue for the criminality of breaking a recommendation, best practice, or commonly accepted procedure if your actions led to an accident, injury, or fatality.